EP0263567A2 - Liquid chromatograph apparatus - Google Patents
Liquid chromatograph apparatus Download PDFInfo
- Publication number
- EP0263567A2 EP0263567A2 EP87201913A EP87201913A EP0263567A2 EP 0263567 A2 EP0263567 A2 EP 0263567A2 EP 87201913 A EP87201913 A EP 87201913A EP 87201913 A EP87201913 A EP 87201913A EP 0263567 A2 EP0263567 A2 EP 0263567A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- pump
- inlet
- solvent
- proportioning valve
- valve arrangement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/26—Conditioning of the fluid carrier; Flow patterns
- G01N30/28—Control of physical parameters of the fluid carrier
- G01N30/34—Control of physical parameters of the fluid carrier of fluid composition, e.g. gradient
Definitions
- the invention relates to liquid chromatograph apparatus comprising a plurality of solvent sources, a solvent proportioning valve arrangement having a separate inlet for each solvent and a single outlet, means for coupling the outlet of the proportioning valve arrangement to the inlet of a pump, means for coupling the outlet of the pump to the inlet of a chromatographic separating column, and means for detecting the constitutents eluting from the column.
- HPLC high performance liquid chromatography
- the mixture may remain constant with time or when using the technique known as gradient elution may be continously or stepwise varied with time. In both cases it is desirable to have as high an accuracy as possible in the proportions of the solvents in the mobile phase.
- the desired composition may be achieved by means of a proportioning valve arrangement which comprises a plurality of solenoid valves or similar devices which connect different solvent sources to the inlet of the pump sequentially during the suction stroke of the pump. The proportion of the duration of the suction period for which any one solvent is connected to the pump inlet determines the proportion of that solvent in the mobile phase.
- the proportioning may take place over more than one pump or piston cycle. Further, as disclosed in our co-pending Application No. 8622328 (PHB33928) the proportioning valve arrangement may be constructed to minimise liquid flow surges caused by quickly operating valves.
- a filter is inserted in each of the solvent supply lines.
- these filters are located within each individual solvent container on the end of the tube which leads from the solvent container to the proportioning valve arrangement.
- the invention provides liquid chromatograph apparatus as set forth in the opening paragraph characterised in that the means for coupling the outlet of the proportioning valve arrangement to the inlet of the pump comprises a filter.
- a number of advantages are obtained by providing a single filter at the inlet of the pump instead of individual filters at each solvent source. If separate filters are used it is likely that there will be a variation in their impedance to liquid flow and consequently in accuracies in the solvent proportions will then occur since the average flow rates of the individual solvents into the pump inlet will vary when switching from one solvent source to another. The variation in impedance to the flow of the solvents will be much reduced without the presence of individual filters since the impedance of the solvent supply tubes is small. The pressure differential in the solvent supply tubes is reduced as the high impedance filter is between the proportioning valve arrangement and the inlet to the pump and this reduces the likelihood of sucking air into the system at the tube joints. A single filter after the proportioning valve arrangement is less expensive than a plurality of separate filters which are necessary prior to the valve arrangement if no subsequent flter is used.
- the filter may be mounted on the inlet means of the pump.
- the major flow resistance on the inlet side of the pump is located adjacent the inlet and hence the pressure differential in the rest of the system is reduced.
- the liquid chromatograph apparatus shown in Figure 1 comprises four solvent reservoirs 1 to 4, which are fed via individual tubes 5 to 8 to the inlets of a proportioning valve arrangement 9.
- the proportioning valve arrangement is electrically operated and is controlled over line 10 from a solvent proportioning control arrangement 11.
- the outlet of the proportioning valve arrangement 9 is fed to the inlet of a pump 12.
- the pump 12 is controlled by means of a pump control circuit 13 over a line 14.
- the outlet from the pump 12 is fed to the inlet of a solvent mixer 15 whose outlet feeds a sample injection means 16.
- the outlet of the sample injection means 16 is fed to the input of a separating column 17 whose outlet is fed to a detector 18.
- the output of the detector 18 is fed to a signal processing and display arrangement 19.
- a second port of the sample injection means 16 is fed with a sample via a sample inlet 20.
- a selected solvent is fed to the pump 12 via the proportioning valve arrangement 9.
- the proportioning valve arrangement 9 selects each of the solvent sources 1 to 4 in proportion to the desired composition of the solvent to be fed to the pump, that is the solvent proportioning control arrangement operates the appropriate valves at the appropriate times to feed either a selected one of the solvents 1 to 4 or to feed in quick succession two or more solvents to the pump inlet during the suction stroke of the pump to provide a mixture of two or more solvents to be fed to the column.
- the pump control circuit 13 controls the speed of the pump to obtain the desired flow rate of the solvent.
- the solvent mixer 15 ensures that the various components of the solvent to be fed to the column are thoroughly mixed together and comprises a tapering enclosed chamber having an inlet located adjacent its larger end and an outlet located adjacent its smaller end.
- the solvent mixer 15 is an optional component of the system and may not be required under all operating conditions. Its use will depend on the system construction and it may be by-passed under certain conditions and in some systems may be omitted. Further, it could be replaced by other forms of solvent mixer either static or dynamic.
- the proportioning valve arrangement 9 may be provided, adjacent to the inlet to each valve, with a chamber having a solvent inlet and a solvent outlet, the chamber being partially occupied by air or a gas or mixture of gases. This chamber is located close to the inlet port of each valve and relatively distant from the respective solvent containing vessel 1 to 4. For details of this proportioning valve arrangement reference should be made to our co-pending Application No. 8622328 (PHB33928).
- Hitherto solvent mixing arrangements using a plurality of solvent sources and a proportioning valve arrangement prior to the inlet of the pump have included separate filters in each solvent supply path.
- the solvent sources have comprised enclosed containers or bottles having a tube leading from them to the corresponding inlet of the proportioning valve arrangement.
- a filter has been provided on the end of the tube within the solvent container to prevent solid particles entering the pump and hence the separating column.
- proportioning valve arrangement which sequentially connects the solvent sources to the pump inlet during the suction stroke of the pump.
- a proportioning valve arrangement 100 is mounted on a base 101 which also carries a pump 102 having a pump head 103.
- Two solvent sources in the form of containers 104 and 105 are connected via respective tubes 106 and 107 to inlets 108 and 109 of the proportioning valve arrangement 100.
- An outlet 110 of the proportioning valve arrangement 100 is connected via a tube 111 to an inlet coupling 112 on the pump head 103.
- the inlet coupling 112 connects the end of the tube 111 to the inlet of the pump head 103 and also serves as a housing locating a filter.
- the pump 102 may be as described in our co-pending Application No. 8523014 (PHB33205).
- FIG. 3 shows the pump head 103 and inlet coupling 112 in cross-section.
- the inlet coupling 112 is a close fit in a recess 113 of the pump head 103.
- An O-ring 114 provides an air and liquid tight seal between the recess 113 and the inlet coupling 112.
- the inlet coupling 112 is circular in cross-section and is provided with a projection 115 on which the tube 111 fits.
- a recess 116 in the inlet coupling 112 houses a PTFE block 117 which locates a disc filter 118 in close proximity to a part spherical depression 119 in the recess 113.
- a passageway 120 extends through the inlet coupling 112 to allow liquid to flow from the tube 111 to the filter 118.
- the pump head 103 comprises three blocks 121, 122 and 123 which are clamped together.
- the blocks 121 and 122 sandwich a spacer 124 which includes a slot 125 to enable a passageway 126 in block 121 to communicate with inlet check valves 127 and 128 housed in block 122.
- the block 122 has two cylinders 129 and 132 machined in it; the cylinders containing pistons 131 and 132 and communicating with respective inlet check valves 127 and 128 and outlet check valves 133 and 134.
- the outlet check valves connect via tubes 135 and 136 to a combining block 137 which has an outlet 137 for connection to the chromatograph column.
- the filter 118 comprises a sintered disc of, for example stainless steel or PTFE.
- the inlet coupling 112 is designed for easy removal from the pump head 103 to enable periodic replacement of the filter 118 as it becomes blocked with debris.
- the inlet coupling 112 could alternatively be connected to the pump head 103 by means of a screw thread or any other means which would allow disconnection to enable the filter 118 to be replaced.
- the filter 118 When the inlet coupling 112 takes the form shown in Figure 2 the filter 118 will not seat firmly against the depression 119 as the resilience of the O-ring 114 will spring the inlet coupling 112 away from the inner surface of the recess 113. Consequently solvent may be able to leak past the filter 118 into the gap between the inlet coupling 112 and the recess 113. However, the O-ring 114 will prevent liquid escaping. This construction is satisfactory in some circumstances but can lead to dead volumes of liquid which may carry over undesirably into different solvent compositions. To avoid this a screw coupling may be provided and the PTFE block 117 extended upwardly around the filter 118 so that when the screw thread is tightened the block 117 seals against the recess and prevents liquid from escaping round the edges of the filter 118.
Abstract
Description
- The invention relates to liquid chromatograph apparatus comprising a plurality of solvent sources, a solvent proportioning valve arrangement having a separate inlet for each solvent and a single outlet, means for coupling the outlet of the proportioning valve arrangement to the inlet of a pump, means for coupling the outlet of the pump to the inlet of a chromatographic separating column, and means for detecting the constitutents eluting from the column.
- In some applications of high performance liquid chromatography (HPLC) it is necessary to form the mobile phase from a mixture of two or more solvents. The mixture may remain constant with time or when using the technique known as gradient elution may be continously or stepwise varied with time. In both cases it is desirable to have as high an accuracy as possible in the proportions of the solvents in the mobile phase. The desired composition may be achieved by means of a proportioning valve arrangement which comprises a plurality of solenoid valves or similar devices which connect different solvent sources to the inlet of the pump sequentially during the suction stroke of the pump. The proportion of the duration of the suction period for which any one solvent is connected to the pump inlet determines the proportion of that solvent in the mobile phase. As disclosed in our co-pending Application No. 8622326 (PHB33296) the proportioning may take place over more than one pump or piston cycle. Further, as disclosed in our co-pending Application No. 8622328 (PHB33928) the proportioning valve arrangement may be constructed to minimise liquid flow surges caused by quickly operating valves.
- In practical embodiments of such solvent proportioning systems a filter is inserted in each of the solvent supply lines. Customarily these filters are located within each individual solvent container on the end of the tube which leads from the solvent container to the proportioning valve arrangement.
- It is an object of the invention to enable the provision of liquid chromatograph apparatus in which two or more solvents can be accurately proportioned into a mixture forming a desired mobile phase, the proportioning taking place at low pressure prior to the pumping system.
- The invention provides liquid chromatograph apparatus as set forth in the opening paragraph characterised in that the means for coupling the outlet of the proportioning valve arrangement to the inlet of the pump comprises a filter.
- A number of advantages are obtained by providing a single filter at the inlet of the pump instead of individual filters at each solvent source. If separate filters are used it is likely that there will be a variation in their impedance to liquid flow and consequently in accuracies in the solvent proportions will then occur since the average flow rates of the individual solvents into the pump inlet will vary when switching from one solvent source to another. The variation in impedance to the flow of the solvents will be much reduced without the presence of individual filters since the impedance of the solvent supply tubes is small. The pressure differential in the solvent supply tubes is reduced as the high impedance filter is between the proportioning valve arrangement and the inlet to the pump and this reduces the likelihood of sucking air into the system at the tube joints. A single filter after the proportioning valve arrangement is less expensive than a plurality of separate filters which are necessary prior to the valve arrangement if no subsequent flter is used.
- The filter may be mounted on the inlet means of the pump. Thus the major flow resistance on the inlet side of the pump is located adjacent the inlet and hence the pressure differential in the rest of the system is reduced.
- An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
- 1 Figure 1 shows in block schematic form liquid chromatograph apparatus according to the invention,
- Figure 2 shows diagrammatically the solvent supply arrangement connected to the inlet of the pump, and
- Figure 3 shows in cross-section the mounting of a filter on the pump head assembly.
- The liquid chromatograph apparatus shown in Figure 1 comprises four solvent reservoirs 1 to 4, which are fed via
individual tubes 5 to 8 to the inlets of aproportioning valve arrangement 9. The proportioning valve arrangement is electrically operated and is controlled overline 10 from a solventproportioning control arrangement 11. The outlet of theproportioning valve arrangement 9 is fed to the inlet of apump 12. Thepump 12 is controlled by means of apump control circuit 13 over aline 14. The outlet from thepump 12 is fed to the inlet of asolvent mixer 15 whose outlet feeds a sample injection means 16. The outlet of the sample injection means 16 is fed to the input of a separatingcolumn 17 whose outlet is fed to adetector 18. The output of thedetector 18 is fed to a signal processing anddisplay arrangement 19. A second port of the sample injection means 16 is fed with a sample via asample inlet 20. - In operation a selected solvent is fed to the
pump 12 via theproportioning valve arrangement 9. Theproportioning valve arrangement 9 selects each of the solvent sources 1 to 4 in proportion to the desired composition of the solvent to be fed to the pump, that is the solvent proportioning control arrangement operates the appropriate valves at the appropriate times to feed either a selected one of the solvents 1 to 4 or to feed in quick succession two or more solvents to the pump inlet during the suction stroke of the pump to provide a mixture of two or more solvents to be fed to the column. Thepump control circuit 13 controls the speed of the pump to obtain the desired flow rate of the solvent. Thesolvent mixer 15 ensures that the various components of the solvent to be fed to the column are thoroughly mixed together and comprises a tapering enclosed chamber having an inlet located adjacent its larger end and an outlet located adjacent its smaller end. Thesolvent mixer 15 is an optional component of the system and may not be required under all operating conditions. Its use will depend on the system construction and it may be by-passed under certain conditions and in some systems may be omitted. Further, it could be replaced by other forms of solvent mixer either static or dynamic. Theproportioning valve arrangement 9 may be provided, adjacent to the inlet to each valve, with a chamber having a solvent inlet and a solvent outlet, the chamber being partially occupied by air or a gas or mixture of gases. This chamber is located close to the inlet port of each valve and relatively distant from the respective solvent containing vessel 1 to 4. For details of this proportioning valve arrangement reference should be made to our co-pending Application No. 8622328 (PHB33928). - Hitherto solvent mixing arrangements using a plurality of solvent sources and a proportioning valve arrangement prior to the inlet of the pump have included separate filters in each solvent supply path. Traditionally the solvent sources have comprised enclosed containers or bottles having a tube leading from them to the corresponding inlet of the proportioning valve arrangement. A filter has been provided on the end of the tube within the solvent container to prevent solid particles entering the pump and hence the separating column. The provision of the separate filters in the sample containers produces a number of problems particularly where accurate proportioning of the solvents is required and proportioning is achieved by means of proportioning valve arrangement which sequentially connects the solvent sources to the pump inlet during the suction stroke of the pump. If there is a difference between the flow resistances of the various filters then the average flow rates of the solvents into the pump will not be equal and hence inaccuracies in proportioning will occur since the timing of the valve switching the proportioning valve arrangement assumes equal solvent flow rates. Since the filters provide a significant flow resistance a pressure differential exists between the inlet of the pump and the solvent sources. This leads to the risk of sucking air into the system if joints between the various tubes, valve inlets and outlet, and the pump inlet are not perfect. By locating the filter at the pump inlet, where the seal can be carefully constructed, the pressure differential in the rest of the solvent supply arrangement is reduced and hence the risk of sucking air into the system is correspondingly reduced. Further by locating the filter after the proportioning valve arrangement the number of filters required is reduced and the cost of the system can be correspondingly reduced.
- As shown in Figure 2 a
proportioning valve arrangement 100 is mounted on abase 101 which also carries apump 102 having apump head 103. Two solvent sources in the form ofcontainers respective tubes inlets proportioning valve arrangement 100. Anoutlet 110 of theproportioning valve arrangement 100 is connected via atube 111 to aninlet coupling 112 on thepump head 103. Theinlet coupling 112 connects the end of thetube 111 to the inlet of thepump head 103 and also serves as a housing locating a filter. Thepump 102 may be as described in our co-pending Application No. 8523014 (PHB33205). - Figure 3 shows the
pump head 103 andinlet coupling 112 in cross-section. Theinlet coupling 112 is a close fit in arecess 113 of thepump head 103. An O-ring 114 provides an air and liquid tight seal between therecess 113 and theinlet coupling 112. Theinlet coupling 112 is circular in cross-section and is provided with aprojection 115 on which thetube 111 fits. A recess 116 in theinlet coupling 112 houses aPTFE block 117 which locates adisc filter 118 in close proximity to a partspherical depression 119 in therecess 113. Apassageway 120 extends through theinlet coupling 112 to allow liquid to flow from thetube 111 to thefilter 118. - The
pump head 103 comprises threeblocks blocks spacer 124 which includes aslot 125 to enable apassageway 126 inblock 121 to communicate withinlet check valves block 122. Theblock 122 has twocylinders cylinders containing pistons inlet check valves outlet check valves tubes block 137 which has anoutlet 137 for connection to the chromatograph column. - The
filter 118 comprises a sintered disc of, for example stainless steel or PTFE. Theinlet coupling 112 is designed for easy removal from thepump head 103 to enable periodic replacement of thefilter 118 as it becomes blocked with debris. Theinlet coupling 112 could alternatively be connected to thepump head 103 by means of a screw thread or any other means which would allow disconnection to enable thefilter 118 to be replaced. - When the
inlet coupling 112 takes the form shown in Figure 2 thefilter 118 will not seat firmly against thedepression 119 as the resilience of the O-ring 114 will spring theinlet coupling 112 away from the inner surface of therecess 113. Consequently solvent may be able to leak past thefilter 118 into the gap between theinlet coupling 112 and therecess 113. However, the O-ring 114 will prevent liquid escaping. This construction is satisfactory in some circumstances but can lead to dead volumes of liquid which may carry over undesirably into different solvent compositions. To avoid this a screw coupling may be provided and the PTFE block 117 extended upwardly around thefilter 118 so that when the screw thread is tightened theblock 117 seals against the recess and prevents liquid from escaping round the edges of thefilter 118. - While it is convenient to locate the
filter 118 at the pump inlet it would be possible to mount it on the outlet of the proportioning valve arrangement and still obtain most of the advantages of the invention. The advantage of equal solvent flow rates would still be obtained as well as minimising the number of components required (and hence the cost of the apparatus). Further the pressure differential caused by the filter would only affect the connection between the outlet of the proportioning valve arrangement and the inlet of the pump. - Clearly alternative constructions could be used and the invention is not limited to the particular form of pump, filter, or proportioning valve arrangement described in the embodiment. The form of the filter may be chosen to suit a particular pump construction or proportioning valve arrangement.
Claims (3)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8624325A GB2195556B (en) | 1986-10-10 | 1986-10-10 | Liquid chromatograph apparatus |
GB8624325 | 1986-10-10 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0263567A2 true EP0263567A2 (en) | 1988-04-13 |
EP0263567A3 EP0263567A3 (en) | 1990-04-25 |
Family
ID=10605542
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87201913A Withdrawn EP0263567A3 (en) | 1986-10-10 | 1987-10-07 | Liquid chromatograph apparatus |
Country Status (5)
Country | Link |
---|---|
US (1) | US4902414A (en) |
EP (1) | EP0263567A3 (en) |
JP (1) | JPS63139252A (en) |
AU (1) | AU611097B2 (en) |
GB (1) | GB2195556B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6780325B1 (en) | 1998-11-18 | 2004-08-24 | Eisai Co., Ltd. | Diffusion promoting apparatus for low flow velocity gradient high-speed liquid chromatography |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2220369B (en) * | 1988-06-10 | 1993-01-27 | Inst Of Child Health | Method for testing body fluids by low pressure liquid chromatography |
US5089124A (en) * | 1990-07-18 | 1992-02-18 | Biotage Inc. | Gradient generation control for large scale liquid chromatography |
US5415489A (en) * | 1993-01-11 | 1995-05-16 | Zymark Corporation | Reciprocating driver apparatus |
US10058835B2 (en) * | 2011-01-19 | 2018-08-28 | Waters Technologies Corporation | Gradient systems and methods |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3799396A (en) * | 1972-06-26 | 1974-03-26 | Du Pont | Method for producing a gradient elution |
US4116837A (en) * | 1978-01-12 | 1978-09-26 | The Upjohn Company | High pressure liquid chromatography apparatus |
US4128476A (en) * | 1977-06-14 | 1978-12-05 | Spectra-Physics, Inc. | Carrier composition control for liquid chromatographic systems |
US4310420A (en) * | 1979-03-14 | 1982-01-12 | Japan Spectroscopic Co., Ltd. | Mobile phase supplying method in the liquid chromatography and apparatus therefor |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2297817A (en) * | 1939-01-30 | 1942-10-06 | Gen Motors Corp | Filter element and method of making the same |
US2400091A (en) * | 1944-09-20 | 1946-05-14 | Du Pont | Molding process |
US2485439A (en) * | 1944-11-24 | 1949-10-18 | Jacobs Co F L | Pump |
US2819209A (en) * | 1952-11-15 | 1958-01-07 | Pall | Porous articles of fluoroethylene polymers and process of making the same |
US2842267A (en) * | 1955-05-23 | 1958-07-08 | Standard Oil Co | Fuel system emergency pump and trap |
US3810716A (en) * | 1972-10-27 | 1974-05-14 | Waters Associates Inc | Check valve and system containing same |
US4018685A (en) * | 1975-10-24 | 1977-04-19 | Union Oil Company Of California | Automatic liquid mixing device |
US4045343A (en) * | 1975-11-10 | 1977-08-30 | Varian Associates, Inc. | High pressure liquid chromatography system |
US4116046A (en) * | 1977-08-05 | 1978-09-26 | Hoffmann-La Roche Inc. | Liquid chromatography system |
US4354932A (en) * | 1980-10-15 | 1982-10-19 | The Perkin-Elmer Corporation | Fluid flow control device |
DE3111614A1 (en) * | 1981-03-25 | 1982-10-07 | Uhde Gmbh, 4600 Dortmund | "VALVE SET FOR HIGH PRESSURE PUMPS" |
US4457846A (en) * | 1982-07-08 | 1984-07-03 | Milton Roy Company | Liquid chromatography methods and devices |
US4595496A (en) * | 1984-06-29 | 1986-06-17 | Millipore Corporation | Liquid composition control |
GB2195474B (en) * | 1986-09-17 | 1991-01-23 | Philips Electronic Associated | Liquid chromatograph |
-
1986
- 1986-10-10 GB GB8624325A patent/GB2195556B/en not_active Expired - Lifetime
-
1987
- 1987-10-07 EP EP87201913A patent/EP0263567A3/en not_active Withdrawn
- 1987-10-07 AU AU79428/87A patent/AU611097B2/en not_active Ceased
- 1987-10-09 JP JP62253950A patent/JPS63139252A/en active Pending
-
1989
- 1989-04-18 US US07/339,936 patent/US4902414A/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3799396A (en) * | 1972-06-26 | 1974-03-26 | Du Pont | Method for producing a gradient elution |
US4128476A (en) * | 1977-06-14 | 1978-12-05 | Spectra-Physics, Inc. | Carrier composition control for liquid chromatographic systems |
US4116837A (en) * | 1978-01-12 | 1978-09-26 | The Upjohn Company | High pressure liquid chromatography apparatus |
US4310420A (en) * | 1979-03-14 | 1982-01-12 | Japan Spectroscopic Co., Ltd. | Mobile phase supplying method in the liquid chromatography and apparatus therefor |
Non-Patent Citations (2)
Title |
---|
INTERNATIONAL LABORATORY * |
ULLMANNS ENCYKLOPAEDIE DER TECHNISCHEN CHEMIE * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6780325B1 (en) | 1998-11-18 | 2004-08-24 | Eisai Co., Ltd. | Diffusion promoting apparatus for low flow velocity gradient high-speed liquid chromatography |
US7229551B2 (en) | 1998-11-18 | 2007-06-12 | Eisai Co., Ltd. | Diffusion promoting device for low flow velocity gradient high performance liquid chromatography |
Also Published As
Publication number | Publication date |
---|---|
AU611097B2 (en) | 1991-06-06 |
EP0263567A3 (en) | 1990-04-25 |
GB2195556A (en) | 1988-04-13 |
AU7942887A (en) | 1988-04-14 |
GB8624325D0 (en) | 1986-11-12 |
GB2195556B (en) | 1990-10-03 |
US4902414A (en) | 1990-02-20 |
JPS63139252A (en) | 1988-06-11 |
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